It's very laudable, proficient and smart to try to find a topic that matches your particular problem or concern and simply reply to it. Such actions help to organize and curate the large body of information we have on the forum and that makes it helpful when people search for solutions.
But...
There's no need to force the issue. If there's not an exact match feel free to start a NEW topic. Don't be shy, new topics can be combined with old topics if necessary
![Smile :)](./images/smilies/icon_e_smile.gif)
More often than not, a lot more time is spent pulling replies out of old topics that just don't belong than the reverse.
So if you are struggling to find just exactly the right topic to post in as a reply then that's a good clue that you should probably just start a new one, and start it in the right sub-forum, of course
Thanks,
Scott